1,769 research outputs found
Self-Adaptive Role-Based Access Control for Business Processes
© 2017 IEEE. We present an approach for dynamically reconfiguring the role-based access control (RBAC) of information systems running business processes, to protect them against insider threats. The new approach uses business process execution traces and stochastic model checking to establish confidence intervals for key measurable attributes of user behaviour, and thus to identify and adaptively demote users who misuse their access permissions maliciously or accidentally. We implemented and evaluated the approach and its policy specification formalism for a real IT support business process, showing their ability to express and apply a broad range of self-adaptive RBAC policies
Self-assembly of multi-component fluorescent molecular logic gates in micelles
A recent strategy for developing supramolecular
logic gates in water is based on combinations
of molecules via self-assembly with surfactants, which
eliminates the need for time-consuming synthesis. The
self-assembly of surfactants and lumophores and receptors
can result in interesting properties providing cooperative
e ffects useful for molecular information processing
and other potential applications such as drug delivery
systems. This article highlights some of the recent advancements
in supramolecular information processing
using microheterogeneous media including micelles in
aqueous solution.peer-reviewe
Molecular structure and the twist-bend nematic phase : the role of terminal chains
Peer reviewedPostprin
Augmenting Bragg Reflection with Polymer-sustained Conical Helix
There has been a recent surge of interest in smart materials and devices with stimuli-responsive properties for optical modulations. Cholesteric liquid crystals (CLCs) are a unique class of light-manipulating materials, and strongly interact with light and other electromagnetic (EM) waves. Because of their intricate helical structure, new properties of CLC have emerged revealing unique optical behavior that has resulted in rewriting Braggsâ law for how light interacts with soft materials. The aim of this work is to push the limits of spectral tuning with a new method of augmenting light-cholesteric interactions using a polymer-sustained conical helix (PSCH) structure. We experimentally explore the reversibility of reflective wavelength modulation and validate the mechanism enhanced by a polymer-sustained helicoidal structure via theoretical analyses. The conical helix structure of a CLC, formed by low-field-induced oblique orientation of cholesteric helices, is comprised of a chiral dopant, a conventional nematic, and bimesogenic and trimesogenic nematics. Polymerizing a small amount of a reactive mesogen in the CLC with an applied electric field produces a templated helical polymer network that enables three switched optical states, including light-scattering and transparent states as well as color reflection in response to an applied increasing or decreasing electric field. An electro-activated PSCH optical film covers a wide color space, which is appropriate for tunable color device applications. We envisage that this PSCH material will lead to new avenues for controlling EM waves in imaging and thermal control, smart windows and electronic papers
Free volume, molecular grains, self-organisation, and anisotropic entropy : machining materials
In this article, the relationship between molecular architecture and the formation of twist-bend phases is reviewed under the context of shape dependency. We conclude that the twist-bend phase is a universal phenomenon, which occurs in a wide variety of materials, for dimers through to main chain polymers. In the process, the chemical information on molecular design is effectively lost or irrelevant, and molecular topology takes precedence over electrostatic interactions in mesophase formation. As a consequence of this macro-scale material, engineering by shape alone becomes a possibility, potentially more phases may be realised, and entropy is anisotropic
Two in one: cryptic species discovered in biological control agent populations using molecular data and crossbreeding experiments
There are many examples of cryptic species that have been identified through DNA-barcoding or other genetic techniques. There are, however, very few confirmations of cryptic species being reproductively isolated. This study presents one of the few cases of cryptic species that has been confirmed to be reproductively isolated and therefore true species according to the biological species concept. The cryptic species are of special interest because they were discovered within biological control agent populations. Two geographically isolated populations of Eccritotarsus catarinensis (Carvalho) [Hemiptera: Miridae], a biological control agent for the invasive aquatic macrophyte, water hyacinth, Eichhornia crassipes (Mart.) Solms [Pontederiaceae], in South Africa, were sampled from the native range of the species in South America. Morphological characteristics indicated that both populations were the same species according to the current taxonomy, but subsequent DNA analysis and breeding experiments revealed that the two populations are reproductively isolated. Crossbreeding experiments resulted in very few hybrid offspring when individuals were forced to interbreed with individuals of the other population, and no hybrid offspring were recorded when a choice of mate from either population was offered. The data indicate that the two populations are cryptic species that are reproductively incompatible. Subtle but reliable diagnostic characteristics were then identified to distinguish between the two species which would have been considered intraspecific variation without the data from the genetics and interbreeding experiments. These findings suggest that all consignments of biological control agents from allopatric populations should be screened for cryptic species using genetic techniques and that the importation of multiple consignments of the same species for biological control should be conducted with caution
The effect of ionic composition on acoustic phonon speeds in hybrid perovskites from Brillouin spectroscopy and density functional theory
© The Royal Society of Chemistry 2018. Hybrid organic-inorganic perovskites (HOIPs) have recently emerged as highly promising solution-processable materials for photovoltaic (PV) and other optoelectronic devices. HOIPs represent a broad family of materials with properties highly tuneable by the ions that make up the perovskite structure as well as their multiple combinations. Interestingly, recent high-efficiency PV devices using HOIPs with substantially improved long-term stability have used combinations of different ionic compositions. The structural dynamics of these systems are unique for semiconducting materials and are currently argued to be central to HOIPs stability and charge-transport properties. Here, we studied the impact of ionic composition on phonon speeds of HOIPs from Brillouin spectroscopy experiments and density functional theory calculations for FAPbBr3, MAPbBr3, MAPbCl3, and the mixed halide MAPbBr1.25Cl1.75. Our results show that the acoustic phonon speeds can be strongly modified by ionic composition, which we explain by analysing the lead-halide sublattice in detail. The vibrational properties of HOIPs are therefore tuneable by using targeted ionic compositions in the perovskite structure. This tuning can be rationalized by non-trivial effects, for example, considering the influence of the shape and dipole moment of organic cations. This has an important implications for further improvements in the stability and charge-transport properties of these systems
Host-pathogen wars: new weapons from biotechnology and genomics.
Pathogens are imminent threats to crop production. Among the management tools available to protect crops from diseases, the use of host-plant resistance had been hindered by a lack of tools and resources to identify resistance genes (R-genes). Genomic technologies have empowered acquisition of a new level and quality of information on plant-pathogen interactions. Next generation sequencing, differential transcriptome analysis, gene editing, and use of bioinformatics have greatly expanded the numbers of R-genes identified, enriched understanding of R-avirulence gene interactions, and disease diagnosis. In this review, we highlight the application of genomic technologies to identification of pathogen machinery for future improvement of host plant resistance
Future scenarios for oil palm mortality and infection by Phytophthora palmivora in Colombia, Ecuador and Brazil, extrapolated to Malaysia and Indonesia
Palm oil is a very important commodity especially to Malaysia and Indonesia. However, Latin American countries have significant industries, particularly Colombia. Climate change (CC) is a highly probable phenomenon which will affect diseases of oil palm (OP) with Phytophthora palmivora causing devastating outbreaks in Latin America and especially Colombia. Furthermore, the oomycete is an endemic pathogen to other crops in Malaysia such as durian, and is capable of causing disease of OP in vitro. A similar disease has been recorded in Thailand. It is crucial that P. palmivora is controlled in Malaysia and Indonesia because the organism is highly virulent, although there are acute and chronic forms. This current paper investigates the effect of CC on P. palmivora disease and on OP survival via a CLIMEX model for future suitable growth of OP. Postulated schemes are provided for Malaysia and Indonesia for acute and chronic forms of the disease which indicate an extremely high and increasing threat, likely to reduce the sustainability of the OP industry by 2050 and further by 2070 and/or 2100. Brazil appears less threatened by the disease under these scenarios, but their OP is likely to have 100% mortality. The chronic and acute forms of the malady present reduced and high threats respectively to Malaysia and Indonesia. The data herein will be useful for, inter alia, plantation managers who will be able to assess the accuracy of these scenarios in the future. Amelioration methods are required urgently and quarantine procedures need strengthening.(undefined)info:eu-repo/semantics/publishedVersio
The legal aspects of connectivity conservation: case studies
This publication follows on from Volume I in the series on legal aspects of connectivity conservation. It provides five case studies that continue to define and develop connectivity conservation law for supporting protected areas and for providing opportunities to address climate change as part of biodiversity conservation agendas. Volumes I and II together aim to advance conceptual thinking and legal understanding about important law and policy tools and options for supporting the connectivity of protected area systems. The legal research and analyses reflected in these papers span international, regional, national and local levels. A range of legal instruments existing in most national legal systems, from conservation and sustainable use laws to land use planning, development control, voluntary conservation and economic instruments are explored
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